1. Field of the Invention
The present invention relates to an optical communication device. More particularly, it relates to an alignment apparatus for connecting an optical fiber block to a planar optical wave-guide element.
2. Description of the Related Art
In general, a planar optical wave-guide element has been used to divide many different wavelengths of optical signals advancing through a single optical path into respective single wavelengths of optical signals advancing through a plurality of optical paths. The planar optical wave-guide element includes at least one input terminal end and a plurality of output terminal ends so as to branch optical signals. There is included a core forming an optical wave-guide path between the input and output terminal ends to branch optical signals. The core is enclosed by a cladding material. Each of the input and output terminal ends is connected by an optical fiber, thus causing optical signals to be input or output.
Typically, an optical fiber block is used to stably connect an optical fiber to the input or output terminal end of the planar optical wave-guide element. The optical block is adapted to arrange a single-cored optical fiber or a multiple-cored optical fiber into a V-shaped groove and then bond the optical fiber with an adhesive such as epoxy or the like, wherein the single-cored optical fiber has a single optical fiber strand, without an outer sheath on its terminal end, arranged into the V-shaped groove, but the multiple-cored optical fiber does generally take a ribbon form and has a plurality of optical fiber strands, without an outer sheath on its terminal end, arranged into the V-shaped groove.
The optical fibers arranged on the optical fiber block as well as on the planar optical wave-guide element as mentioned above must be connected to each other with considerable precision.
FIG. 1 is a perspective view of an alignment apparatus 100 for optical fiber blocks according to a conventional embodiment. FIG. 2 is a side view for describing the operation of the alignment apparatus 100 for optical fiber blocks shown in FIG. 1. As shown in FIGS. 1 and 2, an alignment apparatus 100 for optical fiber blocks in accordance with the conventional embodiment is mounted on an alignment driving actuator 190 and comprises a base plate 111, a lower plate 113, a upper plate 115, a sliding table 117, a jig 119 for locking an optical fiber block, a locking axle 127, a locking driver 125, and a displacement sensor 123.
The base plate 111 includes a first plate 111 a for mounting the alignment apparatus 100 for optical fiber blocks to the alignment driving actuator 190, and a second plate 111b extending in a direction perpendicular to the first plate 111a. The lower plate 113 is mounted to the second plate 111b. 
The lower plate 113 helps to guide the sliding table 117 to move horizontally in a forward or backward direction z, taking a folded form vertically extending from the opposite ends thereof so as not only to mount the locking driver 125 but also to restrict a movable range of the sliding table 117. That is to say, the lower plate 113 is designed so that the movable range of the sliding table 117 is restricted by it and that both the locking driver 125 and the displacement sensor 123 are mounted to it.
The sliding table 117 is intended to finely align an optical fiber block 101 which is locked to the jig 119. When the optical fiber block 101 is locked to the jig 119, the optical fiber block 101 is subjected to a resilient force from a certain resilient means 121 in a direction such that the optical fiber block 101 comes into a close contact to a corresponding counterpart component 102 such as the planar optical wave-guide element. The sliding table 117 is horizontally movable on the lower plate 113 and at the same time is subjected to restriction to the movable range thereof by the configuration of the lower plate 113.
The upper plate 115 is firmly mounted on the sliding table 117 so that it is possible for the upper plate to move together with the sliding table 117. The upper plate 115 is also provided with the jig 119.
The jig 119 for locking the optical fiber block 101 includes a bracket 119a for positioning the optical fiber block 101 and a holder 119b for locking the optical fiber block 101 positioned by the bracket 119a. The optical fiber block 101 positioned by the bracket 119b is locked to protrude forward farther than both the lower plate 113 and the upper plate 115.
The locking axle 127, the locking driver 125 and the displacement sensor 123 are installed on the folded part 113a vertically extending from a rear end of the lower plate 113. Therefore, the sliding table 117 is locked when displacement of the sliding table 117 aligns the optical fiber block 101 in the optimal position. That is to say, the optical fiber block 101 comes into close contact with the counterpart component, such as a planar optical wave-guide element or the like. An end surface of the optical fiber block 101 is aligned parallel to an end surface of the counterpart component. At this position, the sliding table 117 is located at a forefront while the optical fiber block 101 is aligned, whereby the position is sensed by the displacement sensor 123. The locking driver 125 moves the locking axle 127 forward, and thereby locks the upper plate 115.
The alignment apparatus 100 for optical fiber blocks as mentioned above is mounted on the alignment driving actuator 190.
The alignment driving actuator 190 provides the optical fiber block 101 with three dimensional linear and rotational alignments in relation with a x-axis, a y-axis and a z-axis, respectively, wherein the linear alignments are performed along to the respective x-, y- and z-axes, i.e. in a left or right direction x, in an upward or downward direction y, and in a forward or backward direction z; whereas the rotational alignments are performed about the respective x-, y- and z-axes, i.e. in a x-axial rotational direction θx, in a y-axial rotational direction θy, and in a z-axial rotational direction θz.
Referring to FIG. 2, the linear alignments of all the x-, y- and z-axes and the rotational alignment for the z-axis are performed by a lower driving actuator 191. The rotational alignments of the x- and y-axes are performed by first and second upper driving actuators 197 and 199. The lower driving actuator 191 first performs an approximate alignment first and then the upper driving actuators 197 and 199 perform a fine alignment.
Also, for alignments of the three axial linear directions x, y and z, respectively, and three axial rotational directions θx, θy and θz, driving motors are required corresponding to each of the directions. Particularly, for respective fine alignments of the x and y axial rotational directions θx and θy, respectively, driving motors with high precision are required.
Despite these high precision driving motors, the conventional alignment apparatus is flawed in that the motors perform alignment of the x- and y-axial rotational directions, θx and θy respectively, individually, resulting is poor alignment with respect to one another. Moreover, the bracket on which the optical fiber block is positioned is manufactured corresponding to the size of the optical fiber block. Consequently, the bracket should be replaced in order to align another optical fiber block on which another cored optical fiber is arranged.